Summary The study of drug delivery systems for prolonged or triggerable local anesthesia invariably involves measuring the release of drugs into fluids, in vitro and in vivo. In both cases, but particularly in vivo, the drugs may be present at very low concentrations ? too low to be detected by chromatographic means. Also in both cases, the drugs of interest may be present with other compounds that can confound the detection and quantitation of the drug. This problem is commonly overcome with liquid chromatography-mass spectrometry (LC-MS). LC- MS is also useful for chemical reaction monitoring in real time to determine whether we obtain the desired product for sustained and/or triggered release systems and to optimize the chemical synthesis routes. LC-MS is a technique that we have frequently used in our research funded by NIGMS. Access to LC-MS has been a serious bottleneck to our research since there is only one at our institution and it is heavily oversubscribed. Using other institutions' LC-MS is costly, time- consuming (travel), suboptimal for sample stability, and impractical for real time reaction monitoring. We are therefore applying for an administrative supplement to purchase an LC-MS for our lab.